UBIFS: make force in-the-gaps to be a general self-check

UBIFS can force itself to use the 'in-the-gaps' commit method - the last resort
method which is normally invoced very very rarely. Currently this "force
int-the-gaps" debugging feature is a separate test mode. But it is a bit saner
to make it to be the "general" self-test check instead.

This patch is just a clean-up which should make the debugging code look a bit
nicer and easier to use - we have way too many debugging options.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 546ad57..06d171c 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -34,7 +34,6 @@
 #include <linux/moduleparam.h>
 #include <linux/debugfs.h>
 #include <linux/math64.h>
-#include <linux/slab.h>
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
 
@@ -2458,14 +2457,12 @@
 	return 0;
 }
 
-static int invocation_cnt;
-
 int dbg_force_in_the_gaps(void)
 {
-	if (!dbg_force_in_the_gaps_enabled)
+	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
 		return 0;
-	/* Force in-the-gaps every 8th commit */
-	return !((invocation_cnt++) & 0x7);
+
+	return !(random32() & 7);
 }
 
 /* Failure mode for recovery testing */